Brake-shoe.



C. W. ARMBBUST.

BRAKE SHOE.

APPLICATION msn mw 26. wie.

Fabienne@ epb, H, 1917,

@de f f f' /TMW fifi" lid' sns non nien @HABILES W. RMBRST, OF CHICAGO, ILLINOS, ASSIGNOR, BY MESNE ASSIGNMENTS,

TO THE AMERICAN BRAKE SHOE & FOUNJDRY COMPANY, OF WILMXNGTON, DELA.-

WE, A CORPORATION OF DELAWARE.

BRAKE-SHOE.

LZSQAMLS@ Specification of Letters Patent. Ptgmybgd @@9135 1119 :591%

Application led May 26, 1916. Serial No. 59,938.

To all whom t may concern:

Be it known that l, CHAR-rims W. ARM-y Shoes, of which the following is a full,

clear, concise, and exact description,` reference being had to the accompanying drawings,'forming a part of this specification,

My invention relates tof` brake shoes and has for its object the provision of an improved brake shoe with a reduced area of contact, this reduced area being secured by rovision of recesses or holes extending orwardly from the back of the shoe, which holes or recesses are suitably lled with a lubricant or filler.

In acompanion ase Serial l\io.-'-99,937,`

ledli/fa 26, 1916, I set forth a brake shoe with recesses extending backapplication lf set forth a similar bra e shoe rovided with suitable filler for the recesses.

o illustrate the principle involved in this' 'and my said (zo-pending applicatiom itV is.

pointed out that brake shoes are used toretard the motion of vehicles, and the retarding effect is due to the friction between the applied brake shoes and the wheels. i For any given case, the amount (if-friction the retarding edect produces will depend on the materials of which the shoes are made, the weight to the weight or force applied, but is inde pendent of the surfaces 1n contact, the total friction remaining the "same (within practical limits). Furthermore, the coefficient of friction varies with the speed and length of time the running surfaces are. in contact. The coefficient of friction is used to figure the friction between two surfaces iii-sliding contact, and is determined by the nature of the materials in contact.

Rotation ofthe -wheels in the case of a lmoving train is caused by the adhesion .of

tires or rims to the rails. Each oint of the tire surface of a rotating w eel moves around at the same rate as ythe tram moves forward, but when it comes in contact with the rail it is momentarily at rest in relation 'to the forward movement of the train. If pressure be applied to the shoe the wheel contlnues to revolvel at a rate corresponding to the speed of the train, but the rotary motion 1s kept up with more difficulty under ressure than before so that if tractive force 1s not supplied the train will slow down and finally stop. if the pressure on the shoe is gradually increased .the friction between wheel and shoe becomes greater and greater until it first equals and then exceeds the ad- -hesion between the tires and the rail.

As stated above, the tire in contact with the rail being at rest momentaril with reference to the forward motion o the train, the adhesion must be caused by friction. `Wheny the friction of the shoe equals' the adhesive force to the rails, the wheels skid along the rails and the' resistance to its motion is equal to the frictional resistance to the sliding motion of the wheels along therails. 4 Thus it is seen that there are two cases.

' Firstv'lhe'retarding force of the brake shoe against. the wheel which is measured by the coefficient' of friction between the Second: The skidding of the wheels along the rail which force vis measured by the coefficient: of friction between rail and wheel vby the weight on the wheel.

. From the foregoing fact we see the'rail acts in every sense the same-as a brake shoe and bears out the second law of friction, that friction is independentof the extent of the surfaces in sliding contact. ln anyl given case the retarding power is limited to the adhesive force of the wheel to the rail, in whichcase the eXtentof the surfaces in sliding contact is practically only a line the width of the rail. y

l find that in accordance with the above facts l 'am enabled to construct a brake shoe out sacrificing any of the frictional value, and yet insuring longer life of the shoes.

ln one form of the invention which will be .described more in detail later l use a brake shoe whose outline is the same in size as that of the standard brake shoes. l however provide holes in this brake shoe to re yof which'th'e area of the material pressing vagainst the wheel is largely reduced withduce the area of contact, thus saving a large amount of material, making the brake shoe cheaper. Furthermore the provision of these holes permits me to have chilled edges around them and thus to increase the life of the shoe over and beyond what is now obtainable.v y

However, as stated, I avail myself of the recesses thus provided to incorporate with the shoe also. a suitable filler which may be used for lubricating, cleaning, coollng, trimming, or other purposes, as may be desired. Brake shoes heretofore have had 1nserts of various kinds made of various metals and materials different iiroim the metal of the shoe body, in wedged and various shaped sections placed in the mold and cast in the shoe body. These have invariably been cast in the face of the shoe body separately. Wedge shaped holes may have been cast in the face of a shoe bv the use of separate cores or by the pattern with the widest part of said holes in the face and tapering backwardly, and holes with straight edges may have been likewise cast into a brake shoe. ture however are formed by and in the pattern, and they are formed by and in the pattern extending from the back to the face of the shoe body, and they are Jformed by and in the pattern from the back to the face oit' the shoe body in wedge form with the large end of the wedge at the back of the shoe body and gradually tapering toward the face of the shoe body, in the shoe body. Also in this structure the lubricating and other kinds of fillers are forced into the holes from the back of the shoe. This' structure also has a steel back cooperating with said holes to keep the filler in said holes from coming out at the back of the shoe, the tapered hole preventing the iller from being forced out of the face of the shoe.

I will explain various forms which my invention may Vtake more in detail by referring to the accompanying drawing, in which- Figure 1 is a side view partly in section of a brake shoe constructed in accordance with my invention; Fig. 2 is a front face View thereof;

Figs. 3' and 4 are views similar to Fig. 2 of modified forms of the invention, and

Fig. 5 is a view similar to Fig. 2 showing the recesses very much enlarged and showing the shoe as provided with a recessed eX- tension adapted to cooperate with the flange of the wheel.

Referring more particularly to Figs, l and 2, I show a brake shoe having the body portion l and the bacl; portion 2 cast integrally on a steel bach 9. The brake shoe body is provided with recesses or holes Il, 3

The holes in this struc- Leashes which extend entirely through the shoe and e5 -of the holes 3. rIhese holes are then suitably filled with a ller 5 which may be graphite or similar material, wood, sawdust or any lubricating or frictional or cooling or trimming or cutting material, depending on the purposes forl which the material is to lbe used. As stated, the reduction in the area or the brake shoe does notl in any way militate against its rictional characteristics. The filler, however, may be used for a number of purposes as already stated.

In Fig. 8, I show a modified form or the device in which holes '6, -6 are used similar to the holes 3 except that they are round.

In Fig. l I provide a bach having the staggered and diagonally placed holes 7, 7..

In Fig. 5 I shdow the back as being provided with a flanged portion 8 to show the adaptation of a shoe having provisionboth for the tread and the flange of the wheel,

These modifications are shown merely to indicate that I am not dependent upon the outline of the holes to secure the desired effects within practical limits.

From what has been described the nature of my invention will be readily clear to those skilled in the art. Having however thus described several forms which my invention may take, what I claimas new and desireto secure by Letters Patent is:

l. A brake shoe consisting of a shoe body and a metal backing plate, said shoe body having a plurality of wedge shaped holes extending from its back to its face., said holes being larger at the back of said shoe than at its face, said backing pla-te having holes cooperating with the holes in the shoe body, said holes in said back being smaller than the holes in said shoe body.

2. A brake shoe having a plurality of wedge shaped holes extending clear through said shoe and tapering from the bach to the face of said shoe, said holes being filled with a substance, said substance being introduced from the rear oi' the shoe.

3. A brake shoe consisting of a shoe body, and a metal backing plate, said shoe body having a plurality of wedge shaped holes extending from its back to its face, said holes being larger at the back of said shoe than at its face, said backing plate having holes coperating with the holes of said shoe body.

4. Ik brake shoe having a plurality oi"Y holes therein tapering from its face to `back, a filler in said holes, and shoulders Leeepee 5. A brake shoe having a plurality of holes therein tapering from its face to its hack, :i reinforcing plate embedded in the shoe at the hack thereof, said plate and 5 the back portion of the body of the shoel behind the plate haYing registering holes 1therein registering with the holes in front of seid plate but of less diameter to form inwardly olireoted shoulers, enel e :filler in saiol holes. e

ln Witness whereof, l hereunto subscribe my neme this 23rd day oil May, A. D i916.

CHARLES W. ARMBRUST. Witnesses;

L. Jimmieo Hume A flemme, 

